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This is a dilemma I have with my etron, And not sure if it was there from day 1 as I just came to realize.
Today at 27F I drove 60 miles. I started with 70% SOC.
The car showed 2.1 Miles/Kwh avg consumption for the trip (screenshot below).
that means 60 miles / 2.1 = 28.57 Kw of energy should've been consumed.
Again I started at 70 % means (86.5 *.7 = ) 60.55 Kw in tank to start with.
So at the end of the trip I should end up with (60.55 - 28.57 = ) 31.98 kw. Which is (31.98 / 86.5 = ) .36 or 36% SOC at destination.
Guess what. my SOC at destination is 28 %. -- that's a almost 7 Kw difference which is about a tenth of the usable battery pack.
So either 2.1 miles/kwh consumption is not accurate or there is a battery defect/degradation which is causing battery to lose juice beyond consumption.
The problem may possibly be the ambient temperature. 27F is very cold for an EV battery. As the ambient temp drops, both the max SOC the battery can hold (the amount of actual usable charge at a given SOC-point drops) and the battery efficiency can drop as much as 25%. I'm betting you are starting out with less usable capacity than you think. Try this experiment again when the ambient temperature stays in the 70's.
The problem may possibly be the ambient temperature. 27F is very cold for an EV battery. As the ambient temp drops, both the max SOC the battery can hold (the amount of actual usable charge at a given SOC-point drops) and the battery efficiency can drop as much as 25%. I'm betting you are starting out with less usable capacity than you think. Try this experiment again when the ambient temperature stays in the 70's.
thanks for sharing. That sounds like a very reasonable explanation/cause.
let’s see if myself or someone else could retest the same in a warmer climate.
also what temperature range you suggest is optimum for battery performance?
Battery packs having issues isn't unheard of. As others have said, the cold temp might reduce your range, but you should be able to track kWh into and out of the battery like you said and really see what's going on. I would suggest charging to 100% and discharging (by driving) to around 10%. Then charge back up to 100% with a charger that allows you to track energy into the battery. If everything makes sense, then you should be good. Being out of whack by 7kWh overall is a lot and probably not normal.
Also, if you have an issue with your battery (i.e. bank of cells is out), you will notice sub-optimal charging speed when using a DCFC (i.e. when you get to 80% you will be below 50 kW) and / or you might have an issue under max acceleration where you get a power cut off if you have boost enabled in sport mode.
You leave out a lot of variables that could have effected your battery usage:
Did you pre-condition the battery whilst plugged into your charger as well as warming up the interior and seats prior to driving off?
What temperature was the cabin set to during your drive?
How high were the seat warmers set to and how many seats were being heated?
What speeds were you driving at?
Over 11,126 miles my average energy consumption is 2.3 mi/kWh. The summer I’m getting around 2.7 mi/kWh but in the winter I’m lucky to get around 2.0 mi/kWh during my daily drive to/from work, and the above is with pre-conditioning.
Another issue to maybe consider is rounding errors. The display set to miles per kWh is a less precise way than displaying it as kWh per mile. So you are already looking at a potential margin of error of 2.4% simply because of that as you could be getting 2.05 miles in reality but it gets rounded to 2.1.
Battery packs having issues isn't unheard of. As others have said, the cold temp might reduce your range, but you should be able to track kWh into and out of the battery like you said and really see what's going on. I would suggest charging to 100% and discharging (by driving) to around 10%. Then charge back up to 100% with a charger that allows you to track energy into the battery. If everything makes sense, then you should be good. Being out of whack by 7kWh overall is a lot and probably not normal.
Also, if you have an issue with your battery (i.e. bank of cells is out), you will notice sub-optimal charging speed when using a DCFC (i.e. when you get to 80% you will be below 50 kW) and / or you might have an issue under max acceleration where you get a power cut off if you have boost enabled in sport mode.
That's a certainly a good suggestion, but currently I'm using the stock charger which is practically providing no data, but when observing I didn't notice any longer than expected charge times.
You leave out a lot of variables that could have effected your battery usage:
Did you pre-condition the battery whilst plugged into your charger as well as warming up the interior and seats prior to driving off?
What temperature was the cabin set to during your drive?
How high were the seat warmers set to and how many seats were being heated?
What speeds were you driving at?
Over 11,126 miles my average energy consumption is 2.3 mi/kWh. The summer I’m getting around 2.7 mi/kWh but in the winter I’m lucky to get around 2.0 mi/kWh during my daily drive to/from work, and the above is with pre-conditioning.
Your point regarding preheating makes sense and I absolutely agree. In example above, I actually did preheat for < 10 mins, but when started the car, the battery was still at 70 PCT SOC. That's why I didn't mention that and I didn't include it in my math. But I agree a portion of missing 7 KW is that.
I don't believe what you suggested about other variables is entirely true though. The cabin temp and seat warmer should've been built into avg consumption. that's why (as you pointed out too) we get 2.7 m/kw in summer but 2.1 in winter. I was still basing my calculation on avg consumption which takes into account the consumption by those variables.
Another issue to maybe consider is rounding errors. The display set to miles per kWh is a less precise way than displaying it as kWh per mile. So you are already looking at a potential margin of error of 2.4% simply because of that as you could be getting 2.05 miles in reality but it gets rounded to 2.1.
This is a good point too. I also observed there could be some discrepancy if we do 1 or 2 decimal points.
But again 7 KWs (around 10 % of total usable battery pack) is too big of a discrepancy.
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Battery issue or wrong calculation
